1. Field of the Invention
The present invention relates to writing devices such as refillable pencils, ballpoint pens and the like having a writing device body and a cap which removably fits to an outer surface of a head end portion and the tail end portion of the writing device body.
2. Description of the Related Art
A conventional writing device having a writing device body and a cap is described in U.S. Pat. No. 5,221,152.
The writing device is a refillable pencil or the like having a writing device body and a cap. The writing device body comprises three members, namely an axial pipe or tube, a head end portion, and a tail plug. The head end portion is coupled with the head end of the axial pipe while the tail plug is coupled with the tail end of the axial pipe. A core member is mostly housed in the writing device and has a head end writing portion projecting from the head end of the writing device body. The cap has a cap body and a cover fitted to the head end portion of the cap body.
In conventional writing devices cap, is removably fitted to a cap fitting portion formed on the outer surface of the writing device body. Thus, in the case of a refillable pencil, when a user carries it with her/him, the cap may come off the writing device body due to vibration or the like with a potential breakage of a pencil lead, damage to an article, or injury to a user by the pointed end of the pencil lead which projects from the writing device body. In the case of a ballpoint pen, a ball projecting from the writing device body may smudge an article or cause similar damage.
In the case of a writing device like a fountain pen, external threads are formed on the outer surface of the writing device body and internal threads are formed on the inner surface of the cap, whereby the cap is attached to the writing device body by engaging the external and internal threads. This type of writing device makes removal and reattachment of the cap troublesome due to the required turning the cap for its removal and reattachment. Further, when the user carries it with her/him, the cap may loosen or come off due to vibration.